National Engineering Research Center of Navel Orange, Gannan Normal University, Ganzhou 341000, China; South China Botanical Garden, Chinese Academy of Science, Guangzhou, 510650, China.
National Engineering Research Center of Navel Orange, Gannan Normal University, Ganzhou 341000, China.
Fungal Biol. 2022 Mar;126(3):201-212. doi: 10.1016/j.funbio.2021.12.006. Epub 2022 Jan 2.
Blue mold caused by Penicillium italicum is a severe postharvest disease in citrus fruits. In this study, the fermentation product (FP-E) of Aspergillus aculeatus GC-09, an endophytic fungus isolated from a citrus plant, was found to exhibit antifungal activity against P. italicum with a MIC of 0.3125 mg/mL. The fungus A. aculeatus GC-09 was identified based on the studies of morphology and ITS nucleotide sequence. FP-E significantly inhibited the spore germination and mycelial growth of P. italicum. Scanning electron microscopy (SEM) results of P. italicum treated with FP-E showed shrunken, distorted and collapsed hyphae and conidiospores, indicative of the cell membrane damage, which was further confirmed by the propidium iodide (PI) fluorescent staining analysis. Consistent with the microscopy observation, FP-E led to the leakage of cellular constituents from P. italicum, which is evident from the increase in electrical conductivity and nucleic acid contents in the mycelial solution incubated with FP-E. In addition, FP-E treatment considerably increased the intracellular reactive oxygen species (ROS) content, and reduced the enzyme activities of both catalase (CAT) and peroxidase (POD) in P. italicum cells. Furthermore, orange fruits treated with FP-E showed fewer disease symptoms compared to the untreated fruits. These results suggested that the antifungal activity of FP-E might be associated with the disruption of cell membrane integrity, the accumulation of ROS level, and the reduction of the antioxidant enzymes activity of P. italicum. Therefore, A. aculeatus GC-09 might be a potential microbial resource for the biocontrol of citrus postharvest blue mold.
意大利青霉引起的青霉病是柑橘果实采后严重的病害。本研究发现，从柑橘植物内生真菌中分离得到的棘孢曲霉 GC-09 的发酵产物（FP-E）对青霉具有抗真菌活性，其对青霉的最小抑菌浓度（MIC）为 0.3125mg/mL。通过形态学和 ITS 核苷酸序列研究鉴定了真菌棘孢曲霉 GC-09。FP-E 显著抑制青霉的孢子萌发和菌丝生长。经 FP-E 处理的青霉的扫描电子显微镜（SEM）结果显示，菌丝和分生孢子出现皱缩、变形和塌陷，表明细胞膜受到了损伤，碘化丙啶（PI）荧光染色分析进一步证实了这一点。与显微镜观察结果一致，FP-E 导致青霉细胞成分泄漏，这可以从 FP-E 孵育的菌丝溶液中电导率和核酸含量的增加中看出。此外，FP-E 处理显著增加了青霉细胞内活性氧（ROS）的含量，并降低了青霉细胞中过氧化氢酶（CAT）和过氧化物酶（POD）的酶活性。此外，与未处理的果实相比，用 FP-E 处理的橙子果实表现出较少的病害症状。这些结果表明，FP-E 的抗真菌活性可能与破坏细胞膜完整性、ROS 水平积累以及降低青霉抗氧化酶活性有关。因此，棘孢曲霉 GC-09 可能是柑橘采后青霉病生物防治的潜在微生物资源。
